1. Field
The present disclosure relates to a semiconductor device.
2. Related Art
A power semiconductor device for handling electric power from hundreds of kilowatts (KW) to several megawatts (MW) has been used to construct an inverter circuit for an industrial motor or an automotive motor, a power apparatus for a large capacity server, and an uninterruptible power supply (UPS).
One type of a power semiconductor device uses a metal-oxide-semiconductor field effect transistor (MOSFET) semiconductor switch designed to have low on-resistance and a high breakdown voltage. Some of these MOSFETs have a gate electrode in a trench, where the gate electrode is self-aligned to allow the MOSFET to occupy a relatively small area. However, in these devices, an electric field concentrates on a portion of the gate electrode at an edge of the trench. This electric field may lower the breakdown voltage of the device.